LESSON XXXII. 



THE SPINAL BULB. 



The sections described unless otherwise mentioned are of 

 man. The axis of the bulb is fixed in a straight line with the 

 axis of the cord, and sections made approximately at right angles 

 to it. The sections are stained with picrocarmine, so that the 

 grey substance stains deeper than the white substance. 



The sections are to be examined with 1^ to 2 inch objective. 

 In addition they should be observed without magnification, 

 holding them up to the light, or against a white background ; 

 the larger masses of grey and white substance can thus be distin- 

 guished. The groups of nerve cells should be examined with a 

 |rd inch, and in special cases with a Jth inch objective. 



In the description of the sections of the spinal bulb of the 

 dog, the chief points in which they differ from the sections of 

 the bulb of man are noted ; the description given for man is 

 sufficient for the recognition of most of the corresponding 

 structures in the dog. 



1. Section through the lower part of the pyramidal de- 

 cussation. Note : 



The central canal, slightly on the ventral side of the middle 

 of the section. 



The thickened grey mass dorsally of the central canal. 



The ftmiculus gracilis (Goll's column), with elongated 

 patches of grey substance in it the beginning of its nucleus. 



